Cushioned Responsiveness A Zoom Air unit in the forefoot offers responsive cushioning. Every step helps create energy return to help drive you forwards. It's combined with a foam midsole for a firm, yet smooth and stable feeling as your foot hits the ground. Backed By Data Data from hundreds of runners helped inform the crash pad placement at the heel. It helps provide extra cushioning for heel-to-toe transitions. That info was also used to put cooling exactly where you need it on the upper. Flexible and Tough The durable rubber sole is built for mileage. Grooves in the forefoot create flexibility and vertical grooves down the side help create stability.